1. Field of the Invention
Methods and systems consistent with the present invention relate generally to an ad-hoc network. More particularly, the present invention relates to a method for assigning addresses requested by nodes in an ad-hoc network.
2. Description of the Related Art
A typical mobile communication system delivers data between a mobile element and a base station. In such a case, the data is transmitted and received directly between the mobile element and the base station without passing through other nodes. However, an ad-hoc network can take advantage of other nodes for delivering data from a source node to a destination node.
The ad-hoc network is autonomously established by nodes having mobility. Since the nodes are mobile, the structure of the ad-hoc network is highly flexible. The ad-hoc network enables communications between nodes without support provided from an existing mobile communication system, and is not affected by restrictions on the communication distance owing to its support for multihop (i.e., the route between two nodes during communication can consist of more than one hop in that there may be one or more intermediate nodes between the source and destination).
Among the diverse applications of the ad-hoc network, the connection to a server (Internet) will be discussed below. In detail, the discussion is directed to a scheme to access (connect) the ad-hoc network to the server via an Internet gateway (IG).
FIG. 1 depicts an ad-hoc network, a router, a server, and an Internet gateway in accordance with the related art. The Internet gateway interconnects the ad-hoc network and the router.
The ad-hoc network is constructed with a plurality of nodes. By way of example, the ad-hoc network 100 includes a first node 101, a second node 102, a third node 103, a fourth node 104, a fifth node 105, a sixth node 106 and a seventh node 107, as shown in FIG. 1. The nodes 101, 102, 103, 104, 105, 106 and 107 are wirelessly linked to the Internet gateway 110. The Internet gateway 110 is connected to the server 130 via the router 120. The Internet gateway 110 forwards data originated from a node in ad-hoc network 100 to the server 130 and forwards data originated from the server 130 to a node ad-hoc network 100.
To enable communications with the Internet gateway 110, it is required to assign addresses to the nodes in the ad-hoc network 100, from the Internet gateway 110. In response to an address request from one of the nodes in ad-hoc network 100, the Internet gateway 110 selects one of the available addresses and assigns the selected address to the node that has requested the address assignment. Principally, the address allocated from the Internet gateway 110 is valid only within the ad-hoc network 100. That is, such an allocated address is a local address. It is assumed that an identical local address is used in at least two ad-hoc networks. In the case when at least two nodes are assigned the identical local address communicate with the server, the server is not able to discriminate between the at least two nodes.
To overcome the above disadvantages, each node is assigned a global address for communicating with a foreign network, in addition to the local address that is used within the ad-hoc network. Therefore, a novel method is needed to efficiently assign global addresses to nodes so that such addresses do not overlap.